摘要
The as-cast microstructure of AE42 was of typical dendritic and composed of the a matrix and some needle-shaped interphases Al11RE3. A small mount of Ca addition results in significant microstructural refinement and formation of a Al2Ca phase, which showed two kinds of morphologies, lamellar and tiny granular. The former distributes on grain boundaries and the later is within the matrix grains. With the increase of Ca addition the volume fraction of Al-RE compound (Al11RE3) decreases, but Al2Ca increases. Addition of Ca causes a significant increase of yield strength of the alloy both at ambient and elevated temperatures, but a little decrease of the ductility. With calcium addition the ultimate strength decreases at ambient temperature and 150°t, but increases at 175°C and 200°C.
AE4 2的铸态组织主要包含了α镁和少量的针状Al11RE3相 ,呈典型的树枝晶分布 .少量Ca的加入使合金组织细化并形成新相Al2 Ca ,Al2 Ca主要呈现分布在晶界的层片状形貌和弥散在晶粒内部的颗粒状形貌 .随着Ca的加入量增多 ,Al11RE3的体积百分比降低 ,相应Al2 Ca含量增加 .拉伸性能方面 ,Ca的加入使合金的屈服强度在室温和高温下都有显著提升 ,随之延伸率有少量降低 .Ca的加入还使合金在室温和 15 0 ℃ 下抗拉强度下降 .温度的提高使Ca对抗拉强度的影响逐渐加大 ,175℃和 2 0 0℃下 ,随Ca含量的增加抗拉强度逐渐增大 .
基金
TheNationalHighTechnologyResearchandDevelopmentProgramofChina (863Program) (No .2 0 0 1AA3 3 10 3 0 0 1)
